Assembly structure and procedure for concrete towers used in wind turbines

ABSTRACT

Structure and procedure for erecting concrete towers used in wind turbines in which said towers consist of sections, which in turn may each comprise a different number of segments or longitudinal sections. The procedure includes two differentiated cycles, which may take place alongside each other: the pre-assembly of each section of tower and their assembly. The sections may be pre-mounted on bases placed on the ground, with the segment in turn fitted with the help of struts and mechanical clamps. This procedure is extremely versatile in that it makes the best logistic use of the material, resources and requisite assembly times since the assembly procedures for each section can be developed alongside each other in the different wind farm towers, and also greater heights can be achieved than is traditionally possible.

RELATED APPLICATIONS

This application claims the foreign priority benefit, under 35 U.S.C. 119, of Spanish Application No. 200602204 filed on Aug. 16, 2006, the entire contents of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention, structure and procedure for assembling concrete used in wind turbines refers to an original and innovative structure and its associated assembly procedure, for the construction of wind turbine generators in wind farms.

Therefore, the present invention will be of particular interest for the industry supplying wind turbines for making use of wind energy and for the construction industry in respect of civil work for this type of installation.

The structure and procedure which is the object of this invention presupposes an advance in respect of the present State of the Art, although it is based on specific inventions developed by the same holder in a continuously innovative process in this section to which the object of the present invention refers.

In addition, this permits the financially and technically viable development of large concrete towers, which exceed the height of the steel towers traditionally used, and which overcome specific structural problems, in particular vibrations and fatigue which are the chief obstacle to developing height in wind turbines currently installed in commercial wind farms.

It is a well known fact that wind power is currently being developed worldwide and especially in European countries such as Germany, Spain and Denmark.

Following more than a decade of considerable technological advances progressing from dozens of kW to today's MW, it became increasingly clear that there was a need to move towards machines with larger diameter blades (from 90 metres at present) and to a greater hub height reaching over one hundred metres. This development requires new technologies, which will enable the viable construction in terms of costs and time of progressively higher towers.

In this process of advancing the State of the Art, the following three inventions by the same holder of the present invention may be cited as reference since they belong to the same scope of the art.

Thus, utility model U200502266 “Mould perfected for the execution of prefabricated concrete elements for the construction of modular towers for wind turbines”, is an invention consisting of formwork made from metal, PVC, fibreglass or any other material, required to manufacture elements with complicated geometry and strict tolerances, required in the manufacture of towers within the same scope of application as the present invention. This invention satisfactorily resolves specific problems associated with manufacture, using precast concrete, of elements for the construction of modular towers for wind turbines.

In addition, Utility model U200501400 “Perfected structure of joints between plates of modular towers for wind turbines and other applications” consists of an innovative and original structure for joining the plates which make up the aforementioned towers, supporting the wind turbine electricity generators.

Finally, another Spanish invention pertinent to this same state of the art, describes in Utility model U200402304 “Perfected structure of a modular tower for wind turbines and other applications” which consists of another invention by the same inventor which claims the division of the tower into sections limited by horizontal joints and the division of each section of tower into different prefabricated elements, known as segments, in portions, so that they have dimensions and weights which facilitate their transportation from the factory to the wind farm. In this technique the union of the various structural elements is achieved by means of reinforced or pre-stressed connections. All of which implies the need to resolve the union of these elements so that problems of resistance and deformation associated with such unions using different materials in a situation where they require the special characteristics of water tightness and mechanical resistance.

Nevertheless, and despite the advances made in the State of the Art, due to the previous inventions, in order to achieve the objective of creating concrete tower structures with precast parts erected at the final site, which will contribute to the known technology currently used in the State of the Art, it is necessary to devise a structure and procedure which enables it to be carried out in a viable manner with respect to mechanical resistance, therefore resulting in viable costs and execution time constraints, which is the object of the present invention.

SUMMARY OF THE INVENTION

The structure and assembly procedure for the wind turbine concrete towers which is the object of this invention and which is described below, consists of a procedure for erecting the concrete towers consisting of various stages or phases which may be developed at the same time in the different towers of a wind farm, including erection and pre-assembly activities of the sections of each tower of a wind generator in which each section of the tower structure may be composed of a different number of segments or longitudinal sections depending on the situation of that section in the height of the tower. This process comprises two differentiated sequences, one of pre-assembly for each tower section and the erection of said sections, including a pre-assembly phase for each section, a process divided into the following stages, for each section comprising different segments: a phase for the transport and erection of each segment, therefore there being as many phases as there are segments, followed by a final phase comprising filling in of the vertical joints of each section.

In addition, the aforementioned pre-assembly cycle may be carried out for the first section of the wind turbine tower directly on the final site on the base footing or foundation of the turbine whereas the other intermediate section are pre-mounted on assembly bases which are placed on the ground on the platform area provided in the proximity of the base of each wind turbine or on the base itself, placing the segments in their position with the aid of stabilising and bracing struts.

In addition, the erection cycle is begun following the first pre-assembly cycle, in the same wind turbine and this consists of placing each section on the previous one by hoisting with the aid of a crane and fitting it into the connection system of each section.

The Pre-assembly cycle of the first section also includes the following stages as a minimum, in the case of a tower consisting of four segments:

-   -   Verification of the geometry, levelling and implementation of         the foundations and prior placing of the levelling plates with         the pre-adjusted thickness in order to ensure that the support         of the part is horizontal.     -   Coupling of the first segment, using a strut, by the hoisting         bolts of the crown to the erection crane and by the lower bolts         to the other retention crane or to a second pulley tackle of the         erection crane.     -   Tipping of the segment in the air ensuring that the lower         projecting bars (attachment to the base footing) do not collide         and that they are not damaged or bent. Once in the vertical         position the segment is placed vertically in its final location.     -   Lowering of the segment introducing the connection bars into the         jacketing. Adjustment of the end of the strut in the perforated         foundation plate.     -   Checking of the segment position. Adjustment by regulating the         strut or with the crane, and release of the crane.     -   Repetition of the operation of the diametrically opposed         segment.     -   Erection of the third segment, without the strut, connecting to         the two segments already in place using mechanical clamps         located at different heights in the vertical joints.         Verification of the opening of the vertical joints along its         height, checking of the segment position and release of the         crane.     -   Erection of the closing segment, without a strut, attaching it         to the previous ones with the same procedure as in point 3.     -   Introduction of the grills of the vertical joints from the upper         end and any other elements requiring use of the crane.     -   Having erected all the segments checking of the overall         position, including the position of the jacketing and making any         necessary adjustments.     -   Removal of the adjustable struts using the crane.     -   Formwork of the lower horizontal joint and pouring of mortar to         support and fix the first section to the base footing.

After or simultaneous to the pouring of the mortar for the lower horizontal joint, filling in with mortar of the vertical joints.

When sufficient resistance has been achieved in the mortar of the joints, the clamps are removed from the vertical joints.

In addition, the Pre-assembly cycle of the intermediate sections, comprising various segments, includes at least the following stages in the case where there are three segments.

-   -   Placing of the first segment on the pre-assembly bases in a         similar manner to that described for the first section.     -   When placing the second segment as well as acting on the strut,         the clamps of the vertical joint between the two segments are         also tightened.     -   The erection of the closing segment is similar to that of the         closing segment tin the first section and similarly it does not         require a strut.     -   The final section comes pre-assembled from the factory, on a         lorry placed in a horizontal position.     -   The erection cycle carried out with a high-powered crane         consists of placing each section successively on the previous         one, fitting and adjusting the connection system of the         horizontal joints. In order to tip the final section, the lower         end is coupled by encircling the section perimeter using a nylon         belt or similar, fixed at a point on the lower edge of the         section using a metal hook to avoid slipping.

Finally, in the event that the connection system of the horizontal joints is made by fitting passive bars in the appropriate jacketing, using connective mortar, the horizontal joints shall include at least the following stages:

-   -   Production of the non-retractile mortar.     -   Filling of all the jacketing, checking the volume of mortar         introduced.     -   Following controlled filling of the jacketing, pouring of the         mortar, filling the space in the horizontal joint between the         two sections until an adequate thickness is obtained which will         guarantee total contact on the surface of the joint between 2         sections.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a segment (1) with strut (2), clamps (3) and protruding bars (9) and work platform (12), in a structure and procedure for erecting concrete towers used in wind turbines.

FIG. 2 is an illustration of a section (4) with vertical joints (8) between segments, the hoisting bolts (10) and the end of the jacketing (11), in a structure and procedure for erecting concrete towers used in wind turbines.

FIG. 3 is an illustration of the placing of a segment on the support bases (5) for the pre-assembly of a section, coupling to the crown hoist bolts (10) and the lower bolts (13), in a structure and procedure for erecting concrete towers used in wind turbines.

FIG. 4 is an illustration of the erection of sections (4), with horizontal joints (15) in a structure and procedure for erecting concrete towers used in wind turbines.

FIG. 5 is an illustration of the hoisting from a lorry, or flatbed truck of the crown section with the belt (6) and the hook (7) for the coupling of the lower section and coupling elements (14) in the crown in a structure and procedure for erection of concrete towers used in wind turbines.

FIG. 6 is an illustration of the positioning of a segment on the support base (5) with the transmitter (16) of the vertical laser beam (19) and the target (17) fixed on a light structure (18) in a structure and procedure for erecting concrete towers used in wind turbines.

FIG. 7 is an illustration of the positioning of a section of the transmitter (16) of the vertical laser beam (19) and the Diana (17) fixed to a light structure (18) in a structure and procedure for erecting concrete towers used in wind turbines.

DETAILED DESCRIPTION OF THE INVENTION

Below a detailed description is given of the procedure for erecting the concrete towers used in wind turbines, which are the object of this invention, with reference to the accompanying drawings, which represent, merely as an example which is in no way restrictive, of the preferential form of realisation susceptible to all those detailed variations which do not presuppose any fundamental alteration to the essential characteristics of the improvements.

According to the example of execution represented, the procedure for erecting concrete towers used in wind turbines illustrated in this preferential form of realisation consists basically of various stages or phases which may be developed at the same time on a parallel basis with the various towers in a wind farm, thus making optimum logistical use of the resources, materials and times necessary for assembly.

The aforementioned procedure includes two different cycles of activity, which may be developed alongside each other: the pre-assembly cycle and the erection cycle. In the example of realisation illustrated, both cycles have the same productive capacity: two towers per week. The pre-assembly cycle begins its activities some weeks beforehand, so that there is always a minimum advantage of having various towers in the erection cycle, thus avoiding interference of one over another.

Each section (4) of the tower structure may be composed of different number of segments (1) based on their position in the height of the tower. Thus, in this example, an 80 metre high tower, the first section (0-20) corresponding to the first twenty metres of height of the tower is made up of four segments, each limited by vertical sections (8) of that section of tower. The second section (20-40) between twenty and forty metres of the tower height, is composed of three segments, as well as the third section (40-60) that is, at a height of forty to sixty metres of the tower height which is also composed of three segments. The fourth section (60-80) however, comprises two segments, which come already pre-assembled in the factory in one single part.

The aforementioned pre-assembly for each section consists of a procedure divided into the following phases, for each section comprising different segments: one phase for transport and erection of each segment, therefore there are as many phases as there are number of segments, followed by a final filling stage of the vertical joints (8) of each section.

Thus, in the present example of realisation the pre-assembly of the first section (0-20) will be carried out in six stages, one comprising the arrival and assembly of each of the four segments, a fifth phase for filling the horizontal joint with the base footing and a sixth phase of filling the vertical joints, whereas the two following sections (20-40) and (40-60) shall be erected in four phases each, three for the arrival and erection of each segment and a fourth for filling the vertical joints.

The pre-assembly of the first section can be directly carried out on the base footing or foundation of the wind turbine, while the other intermediate sections shall be erected on mounting bases (5), which may be placed on the ground in the zone of the platforms provided in the proximity of the base of each wind turbine, or on the base itself in a position next to the tower.

Therefore, the aforementioned cycle of erection, is initiated following the first pre-assembly cycle in the same wind turbine, and consists of the placing of each section on the previous one; in this case, the placing of three sections each 20 metres high. In this operation each section is hoisted with the aid of a crane.

Therefore, the pre-assembly cycle is begun with erection of the segments of the first section of the present structure of each concrete tower for wind turbines, which in this preferential form of realisation comprise the 20 first metres of the tower. The structure of the aforementioned first section comprises four segments (1) in the form of a section of the trunk of a straight or curved generator cone provided with hoisting bolts (10) enabling them to be mounted directly onto the definitive foundation. Thus the pre-assembly of the first section of each tower comprises the following stages:

-   -   1. Verification of the geometry, levelling and implements of the         foundations and the prior placing of the levelling plates with         the pre-adjusted thickness for obtaining levelling of the part.         The initial thickness of the plates is 20 mm.     -   2. The segments are transported and arrive at the site and are         not stored at the wind farm but are placed directly from the         lorry onto the foundation (or on the pre-assembly bases in the         case of the segments in sections 2 and 3).     -   3. In the lorry the first segment is coupled by the hoisting         crown bolts to the erection crane and by the lower bolts (13) to         another retention crane or to a second pulley tackle of the         erection crane.     -   4. The segment is turned in the air ensuring that the protruding         lower bars (9) (of the attachment to the base footing) do not         collide or are damaged or bent. Having achieved the vertical         position, the lower retaining bolts (13) are released and the         segment hangs solely from just the crown bolts (10). The segment         is then placed upright in its final location.     -   5. The segment is lowered placing the connection bars in their         jacketing. As the segment is lowered the strut 2 is activated in         order to adjust the end of the perforated plate of the         foundation.     -   6. The position of the segment is checked. This is adjusted         using the strut or the crane, increasing or reducing thickness         of the levelling plates if necessary.     -   7. The operation is repeated with the diametrically opposed         segment.     -   8. Erect the third segment, connecting it to the two segments         already fitted by means of mechanical clamps (3) located in the         vertical joints. With the segment at the appropriate height,         tighten the clamps and check the opening of both vertical joints         (8) along their height. The segment position is checked and the         crane is released.     -   9. The fourth closing segment is erected by attaching it to the         two first segments using the same procedure as with the third         segment.     -   10. Having erected the 4 segments, the overall position is         checked once more and any necessary adjustments made     -   11. The grills of the vertical joints are introduced from the         upper end 12. The 2 struts (2) are removed using the crane at         the upper part of the section and any other elements required         are introduced using the crane.     -   13. Formwork is laid around the horizontal joint of the base         footing using a 5 cm high frame outside and inside the segments,         separating their faces at a distance of 5 cm, the non-retractile         mortar is then poured.     -   14. Previously, after or simultaneous to the pouring of the         mortar for the lower horizontal joint, the mortar is poured in         the vertical joints.     -   15. Having achieved sufficient resistance in the mortar of the         vertical joints, the clamps (3) of the vertical joints are         removed.

The procedure continues with the pre-assembly of sections 2 (20-40 m) and 3 (40-60 m).

The procedure is similar to that of erection of the first section except that it is carried out on provisional foundation using (5) pre-assembly bases and with the following differences:

-   -   The first segment erected is provided with a cross bracing         support (2) in order to guarantee its provisional stability.     -   For the second segment it is necessary to tighten the clamps (3)         of the vertical joint.     -   The erection of the third closing segment is similar to the         closing segments of the first section.     -   The lower horizontal joint will not be concreted.

Below the procedure for erecting the concrete towers used in wind turbines continues with the erection of the sections (4) pursuant to the following stages:

-   -   1. Placement of levelling plates on the crown of the first         section.     -   2. Placement around the edge of a profile of self-adhesive foam,         tangential to the external edge of the surface of the crown of         section 1°, and a profile with an L shaped section which serves         as internal formwork.     -   3. Coupling of the crane to the crown bolts (10) of the second         section, using slings.     -   4. Access to the platform (12) of the previous section (the         first). Lifting of the second already pre-assembled section, and         placement in its final location.     -   5. Lowering of the section, introducing the protruding         reinforcement (9) into the jacketing (11) of the first section         until it rests on the levelling plates.     -   6. Checking of the level of the second section. Correction of         the position, if necessary acting on the thickness of the steel         plates, while suspending the section with the crane.     -   7. Access to the upper platform (12) of the second section in         order to uncouple the crane.

This procedure is repeated for the third section.

Erection of the fourth section, according to the following stages:

-   -   1. The fourth section is pre-assembled in the factory, on a         lorry. Using slings the erection crane is coupled by 2 metal         coupling elements (14), which are screwed to the section crown.         Another retaining crane or other pulley tackle from the same         crane will hook onto a belt (6) surrounding the section at         approximately one metre from the lower end and which passes         through a hook (7) which holds the lower rib of the section and         stops the belt from slipping in the turning operation.     -   2. The fourth section is raised approximately one metre and the         transport vehicle is removed.     -   3. The section is then turned by lifting the upper end with the         erection crane while the crane, or second pulley tackle         retaining it holds the lower end at sufficient height to ensure         that the protruding bars (9) do not hit the ground.     -   4. Having achieved a vertical position, the crane or second         retaining pulley tackle releases the load, transferring the full         load to the erection crane. The belt and the coupling from the         lower end are removed.     -   5. The fourth section is located on top of the third section and         a similar procedure is followed for placing the second and third         sections in their final position. In order to realise the         horizontal joints (15) where the system for joining the         horizontal joints is by fitting passive bars (9) in jacketing         (11) with connective mortar, the following stages will be         followed:     -   1. The non-retractile mortar is produced using a special mixer         with a dosage specified according to the manufacturer         instructions.     -   2. Firstly, all the jacketing of each joint are filled, checking         the volume of the mortar introduced. There are openings in the         head of all the jacketing in order to facilitate this operation.     -   3. Following controlled filling of the jacketing, the mortar is         poured, filling the space of the horizontal joint (15) between         sections.

Finally, the form materials and dimensions and number of parts may vary, and in general anything which is an accessory or secondary may be employed provided that it does not alter, change or essentially modify the improvements described herein. 

1. A method for erecting a concrete tower for a wind turbine wherein said tower comprises sections, at least some of said sections further comprising longitudinal segments, said method comprising the steps of: transporting said longitudinal segments; erecting longitudinal segments to form at least a first section of said tower; filling a lower horizontal joint of said first section with mortar; filling vertical joints of said first section with mortar; erecting longitudinal segments to form at least a second section of said tower; placing said second section on top of said first section; and filling a horizontal joint between said first section and said second section with mortar.
 2. The method of claim 1, further comprising the step of placing a third section on top of said first and second sections.
 3. The method of claim 2, wherein said third section comprises a complete section, said complete section being assembled prior to being delivered to a wind farm.
 4. The method of claim 1, wherein said segments of said first section are erected directly on a base footing of a tower.
 5. The method of claim 1, wherein said segments of said second section is erected on a mounting base.
 6. The method of claim 5, further wherein said segments are secured in position by stabilizing struts.
 7. The method of claim 1, further comprising the steps of securing said second section to a crane and using said crane to place said second section on top of said first section.
 8. The method of claim 1, further comprising the step of inserting protruding bars from said first section into corresponding openings in a jacketing of said first section.
 9. The method of claim 1, further comprising the step of verifying a correct position of said at least second section by placing a laser light transmitter substantially in the center of an inside surface of one section and placing a target substantially in the target of a second section, and observing a deviation of a laser point with respect to a center of said target, wherein when said deviation is observed further comprising the step of adjusting a position of a section.
 10. The method of claim 1, wherein said first section comprises at least a first a second and a third longitudinal segment.
 11. The method of claim 10, further comprising the step of coupling a strut, said strut having a first end and a second end to one or both of said first or said second longitudinal segments prior to adding said third segment.
 12. The method of claim 11, wherein said strut is adjustable in length.
 13. The method of claim 12, wherein said first end of said strut is fixed to a point on said segment and said second end of said strut is anchored to a metal perforated plate, said perforated plate lying substantially parallel to the ground.
 14. The method of claim 1, further comprising the step of temporarily securing said segments to each other with mechanical clamps.
 15. The method of claim 1, wherein a plurality of said towers are constructed essentially simultaneously using said steps of said method.
 16. A concrete tower for a wind turbine, said tower comprising at least two tower sections, each of said sections comprising longitudinal segments said longitudinal segments further comprising a mechanical clamp for connecting said longitudinal segments together; said tower sections further comprising vertical joints between said longitudinal sections and horizontal joints between each of said at least two sections; said vertical joints and said horizontal joints being fillable with mortar.
 17. The tower of claim 16 further comprising at least a first, a second, a third and a fourth section, wherein said first, second and third sections are assembled on a site wherein said tower is erected said fourth section being pre-assembled remotely from said site. 